The effect of four microbial products on production performance and water quality in integrated culture of freshwater pearl mussel and fishes

An 80-day mesocosm experiment was conducted to evaluate the effect of four commercial microbial products on production performance and water quality in integrated culture of freshwater pearl mussel Hyriopsis cumingii, grass carp, gibel carp, silver carp and bighead carp. Five treatments were tested. One treatment with non-supplementation of microbial products served as control (C). In the other four treatments, Novozymes Pond Protect (NO), Bio-Form BZT-Water Reform (WR), Bacillus natto (BN) and Effective Microbes (EM) were added at the intervals of two weeks, respectively. Mussel yield declined in the tanks with supplementation of the microbial products. No significant differences were found in fish yield and chemical water quality among the treatments except total nitrogen (TN) was higher in tanks EM than in tanks C. Biomass of phytoplankton and Cyanophyta was higher in tanks NO, WR, BN and EM than in tanks C. Supplementation of the microbial products resulted in change in bacterial community in which Actinobacteria, Chlorobi, Verrucomicrobia and Proteobacteria dominated. Bacterial community in the tanks was significantly affected by TN, total phosphorus, chemical oxygen demand and Cyanophyta biomass. This study reveals that the function of these microbial products as probiotics is limited in H. cumingii farming.